Characteristics of changes in bone mineral density and body composition in obesity patients after metabolic and bariatric surgery: A prospective cohort study

Abstract Aims To explore the changes in bone mineral density (BMD) and body composition in patients after bariatric surgery using dual‐energy X‐ray absorptiometry (DXA) and quantitative computed tomography (QCT), analyse the relationships between these changes and weight loss, and the correlations between the parameters of DXA and QCT. Materials and Methods Sixty‐five patients who underwent surgery between March 2022 and September 2024 were prospectively enrolled. BMD and body composition were measured by DXA and QCT before and after surgery. Laboratory tests were performed. Results The area BMD (aBMD) of lumbar spine (LS) decreased by 3.19 (0.09, 6.50) %, the aBMD of femoral neck decreased by 8.35 (4.66, 12.77) %, the aBMD of total hip decreased by 6.78 (3.98, 10.43) %, and the volumetric BMD (vBMD) of LS decreased by 1.57% ± 8.83%. ΔvBMD was smaller than ΔaBMD‐LS ( p  < 0.05). BMI, fat tissue in the whole body and trunk, and lean soft tissue (LST) all decreased significantly ( p  < 0.05). The reduction rate of visceral adipose tissue was significantly higher than that of subcutaneous adipose tissue ( p  < 0.05). There was a weak positive correlation between ΔBMI and ΔaBMD‐LS ( r  = 0.254, p  < 0.05), and ΔBMI was positively correlated with the changes in various body compositions ( p  < 0.05). Conclusions The decline of BMI after surgery was accompanied by a decrease in BMD, fat and LST content, with different proportions of decrease. Our findings indicate that QCT can serve as a supplementary method for postoperative follow‐up of BMD and body composition in patients undergoing bariatric surgery.